Pulse generators



1956 D. s. RADMACHER 2,769,909

PULSE GENERATORS 2 Sheets-Sheet 1 Filed Feb. 3, 1954 INVENTOR. DONALD s. RADMACHER 1956 D. s. RADMACHER 2,769,909

PULSE GENERATORS 2 Sheets-Sheet 2 Filed Feb.

FIG.4.

FIG.6.

INVENTOR.

DONALD S. RADMACHER BY 2g 76 a a g AGENT United States Patent PULSE GENERATORS Donald S. Radmacher, Van Nuys, Caiifl, assignor to Stoddart Aircraft Radio 00., Inc., Los Angeles, Calif., a corporation of California Appiicatiou February 3, 1954, Serial No. 407,890 19 Claims. (Cl. 250-37) This invention relates to an electro-mechanical device for generating electromagnetic wave pulses of brief duration and of wide frequency spectrum.

The generator consists of a short section of open-circuited coaxial transmission line. The outer conductor is held at ground potential and the inner conductor is alternately connected to a constant potential and removed therefrom to be discharged through a low impedance. The line is mechanically moved a small amount in order that this be accomplished. Driving means eifecting automatic adjustment of the mechanical operation are utilized. The useful energy is taken from a stationary transmission line abutting the movable section.

One particularly useful property of this generator lies in the fact that the amplitude of the voltage output remains constant per given unit of bandwidth from very low to very high radio frequencies. Although a fundamental property or" the coaxial transmission line accounts for the functioning of the oscillator, I have found that a number of factors must be given consideration if a really useful embodiment is to be attained;

It is an object of my invention to provide a pulse oscillator having a-discharge circuit separate from the charge circuit thereof.

Another object of my invention is to provide driving means having inherent mechanical adjustment for accomplishing the motion required to attain the abovementioned separation.

Another object is to provide a novel contact structure characterized by uniform operation and long life.

Still another object is to drive the movable section of line according to a time-distance relation giving a desirably rapid speed of transport.

Still another object is to provide an oscillator giving an output response proportional to tangible parameters.

Still another object is to provide an oscillator giving a minimum subsequent response for repeated closings of the discharge contacts on a single throw, should this be occasioned by a dynamic condition described as bounce.

Still another object is to providea generator which may be driven in a variety of ways.

Other objects of my invention will-become apparent .upon'reading the following details specification and upon examining the related drawings, in which:

Fig. 1 shows a side elevation view of my oscillator, in section, a

Fig. 2 shows an exploded perspective view of the'functional essentials of Fig. 1,

Fig. 3 shows a schematic electrical diagram of my oscillator and means to drive the same,

Fig. 4 shows a side elevation view of'an alternate embodiment of my oscillator, in partial section,

Fig. 5 shows still another embodiment of my oscillator, pneumatically driven, in partial section, and

Fig. 6 shows an o-scillogram of the pulse Waveshapeof the electrical output of my oscillator.

Describing now in detail my generator, synonymously Patented Nov. 6, 1956 conductor of a coaxial radio frequency transmission line. In this practical embodiment conductor 1 is surrounded by a similar hollow cylindrical tube 2 to increase the mechanical strength of the assembly in fastening the same to other apparatus. Inside said outer conductor is a close-fitting metallic shim 3 and within that a sleeve 4, the inner surface of which forms the inner effective surface of the discharge coaxial line, of which cylinder 5 is the inner conductor. A sleeve of smaller internal diameter 6 fits within conductor 1 on the charge side of the line, to the right of center in Fig. 1. All of the abovementioned parts are of non-magnetic material, such as brass, silver plated brass or copper.

A magnetic circuit surrounds this assembly. This circuit is composed of cups 7 and 8, annular disk 9, sleeves 1t) and 11, and a movable section of the inner conductor of the coaxial line known as the plunger, 12. These are constructed of a ferromagnetic substance such as cold rolled steel. Two multi-turn coils 13 and 14 are housed within the cups 7 and 8.

Plunger 12 is free to translate within sleeve 15, of insulating material. An annular insulating washer 16 fits against this sleeve and metallic sleeve 6 on the charge side of the device and a similar insulating washer 17 similarly fits against sleeve 15 and metallic sleeve 4 on the discharge side. The former holds bushing 18, which in turn supports charging contact 19 with lock nut 20. The latter holds discharge contact 21 and lock nut 22. Plunger 12 is titted with a cylindrical section 23 of appropriate contact material, such as platinum, which is turned down accurately concentric to very small active contact portions of cylindrical shape projecting from either end of the plunger. These make and break contact with similar material on disk-like contacts 19 and 21.

Element 24 is a multi-megohm resistor. A metallic sleeve 25 surrounds the exterior lead 26 thereof to form a coaxial lead-through capacitor having hollow dielectric cylinder 27. Sleeve 6 forms the other plate of the capacitor. Equivalent integrally fabricated lead-through capacitors may, of course, be employed.

On the discharge side of the device a disk-like metallic coating 28 is deposited upon washer 17. This makes contact with terminal 21 and shim 3, thence to other of the nested outer coaxial conductors such as 4.

The description of my pulse generator continues with reference to a typical driving and energizing circuit as shown in Fig. 3, after which the mode of operation is discussed in connection with Figs. 1, 2, 3 and 6. In Fig. 3 the electrical representation of the device shown in Fig. 1 is given at the top of the figure and the circuit of a suitable multivibrator relaxation oscillator is given below. Elements found in both figures are given the same reference numeral although the schematic representation may differ from the pictorial one.

Cathodes 31 and 32 of a twin triode vacuum tube 33 are connected to opposite ends of coils 13 and 14, the

termed oscillator, numeral 1 in Fig. 1 indicates the outer other ends being connected together and to ground. The midpoint of heater 34 is similarly connected to ground, this element being energized by battery 35 or an equivalent electrical source of power. Anodes 36 and 37 are connected through resistors 38 and 39 having substantially equal values to anodes voltage source battery 40 or an equivalent. Grids 41 and 42 are connected to ground through substantially equal resistors 43 and 44. Cross capacitors 45 and 46 connect between grids and plates of opposite triodes and are of substantially equal capacitance in this typical multivibrator, which thus produces a square wave voltage output. Approximately a square wave of current flows in coils 13 and 14.

Under open circuit conditions contact 19 assumes the potential of battery 47. This potential is either positive or negative with respect to ground depending upon the position of switch 48, the polarity preferably being changed each time the device is put in operation to prevent unilateral deposition of the metal of the contacts coacting with plunger 12. Resistor 49 and capacitor 50 comprise a power supply isolation filter and resistor 24 in combination with capacitor 6-25 a radio frequency isolation filter. Ferromagnetic element 9 is shown in Fig. 3 to schematically illustrate magnetic coaction between the coils and plunger.

The pulse generator operates as follows. Consider an instant of time in which current is flowing through coil 14. It will be noted from Fig. 1 that sleeve 10 does not extend to disk 9. Thus, there is a gap in the magnetic circuit comprised of sleeve 10, cup 7 and disk 9. Plunger 12 is in this gap and it is ferromagnetic. Being free to move it takes a position most nearly closing the gap. This is accomplished when the righ-hand point of plunger contact 23 is in contact with charging contact 19. Plunger 12 thus takes on the potential of that contact, of value determined by battery 47. Consider now another later instant of time, when current has ceased to flow in coil 14 and instead flows in coil 13. Because of the symmetrical magnetic structure the previous action will be repeated, but in the opposite direction, so that plunger 12 moves into contact with discharge contact 21.

The transport of plunger 12 from one contact to the other is relatively rapid and the arc-like phenomena which come into play at the instant of contact results in a current pulse flowing at discharge contact 21 of very short duration, of the order of 10- seconds. In micro wave terminology the current pulse persists for the period of time required for the current to flow from the contact through disk resistor 28, along the inner surface of outer coaxial conductor 1 to the right hand end of plunger 12 and back to the point of beginning. This flow takes place at approximately the speed of propagation of light; that is, the speed of light divided by the square root of the dielectric constant of the separating material 28. This flow is followed by a second one of considerably reduced amplitude. A highly damped wave is secured, as shown in Fig. 6, in which the major portion of the energy is contained in the first flow, represented by the first pulse 55 in Fig. 6. The extremely rapid rise 56 accounts for energy over an extremely wide bandwidth of radio frequencies. The form of the pulse shown in Fig. 6 is the same for either voltage or current, the two being merely displaced somewhat in time due to an impedance ratio utilized, to be discussed later.

.The repetition rate of the pulse group shown in Fig. 6 depends upon the time of a full cycle of a square wave of the multivibrator energy through coils 13 and 14. This has an upper limit depending upon the ratio of the mechanical inertia of plunger 12 to the driving force exerted, which theoretically can be quite high. Practically, values from a few cycles to a few hundred cycles per second are useful. Plunger 12 may be drilled longitudinally with holes for reducing inertia as indicated in Fig. 3 and the size and ratio of diameter to length is capable of considerable variation, these parameters also having an effect on the microwave limit of the radio frequency energy.

The ratio of surge impedance of the coaxial line formed by the inner line, plunger 12, and outer conductor 1 to that of the resultant discharge impedance, formed by the resistor upon disc 28 in parallel with the surge impedance of the output transmission line, conductors 4 and 5, is preferably 0.74. This ratio is particularly appropriate when the relation of constant output voltage per unit of bandwidth over a Wide frequency spectrum is desired.

The highest radio frequency for which this relation holds 1s:

where,

c=velocity of light in meters per second e=dielectric constant of the dielectric involved, 1. e., 15 l=discharge path length in meters In practice my device may often be constructed with a longer plunger of smaller diameter than that shown. Element 12 is susceptible to wide variation in size and shape as a matter of design according to the expression given above. Furthermore, this relation, though desirable when the device is used for calibrating purposes, need not be followed in accomplishing other operational objectives.

The exploded view of Fig. 2 is helpful in visualizing the functional essentials of my oscillation generator. The position of resistor disk 28 as making contact with both inner conductor 5 and outer conductor 4 is to be noted. Shim 3 (Fig. 1) is utilized in practice to insure good contact with the resistor material, however, because of the presence of the dielectric washer with disk 28, shim 3 has essentially the same impedance to inner conductor 5 as the inner surface of conductor 4. In practice, the resistance of disk 28 is often ten ohms and the characteristic impedance of line 45 fifty ohms. These low impedances cause relatively large currents to flow and reduce the effect of contact resistance at the discharge contacts. Wide departures from these values are possible without departing from the teaching of my invention. Similarly. subject to variation, a practical value for resistor 24 is ten or more megohms and for the potential of battery 47 of the order of a few to a few hundred volts each side of ground.

Plunger 12 is preferably fitted into insulating sleeve 15 as a free but close slide fit. Smooth surfaces and careful workmanship are desirable. The cylindrical extensions of contact material 23, which comprise the actual contacts, are preferably concentric with the outer surface of.

. the plunger. In order to improve the contacting process over other arrangements and to minimize inescapable shortcomings in the above-suggested precision, I have found that the structure illustrated, where the movingcontacts are small cylinders and the stationary contacts are flat disks, gives best performance and longest useful life. In order that blackening of the working contact area be avoided it is desirable to hold the small cylinder diameter to not in excess of six-thousandths of an inch. These tolerances are in order when my oscillator is intended for precise operation in instrument-type devices; for a high power embodiment other factors would govern and sizes increase. I

There is no upper limit to the length of the discharge line represented by inner conductor 5 but the same should be sufficiently long to contain at least a few wavelengths corresponding to that of the pulse. The distance over plunger 12 previously described corresponds to a quarter. wavelength. It will be noted that the charge circuit is separated from the discharge circuit in my oscillator in view of the travel of plunger 12 between the two contacts 19 and 21. Although this travel may be only of the order of ten to thirty thousandths of an inch in practice it represents a complete break insofar as the radio frequency performance of the device is concerned. This has advantages.

With this configuration the plungercharge voltage and the discharge load resistance (28) are definite values determinable by ordinary measurements yet holding at the highest radio frequencies involved and therefore of value as a calibrating reference. Were the charge circuit constantly connected this relation would be complicated, largely destroying the desired reference.

Also, should the discharge contacts come together more than once in a discharge cycle due to a mechanical dynamic instability which may be simply described as bounce, a condition of partial recharge of the plunger does not occur as would happen were the charge circuit wave of the alternating current through the coil. the half cycle when the polarity of the magnetic field of continuously connected to the plunger. A uniquely metered charge is transported. by the isolated moving plunger. Bounce is never sufficiently severe to cause the plunger; to return to the charge terminal. Rather, it is an oscillation close to the discharge contact 21. When more. than uniformly recurrent charges are impressed upon the discharge circuit the oscillator becomes unreliable for all uses in which the energy of the discharge pulse bundle should be constant. One such use is the measurement of the noise factor of an intermediate frequency amplifier.

A mechanical advantage accrues from the use of the plunger. Blows thereof against the charge and discharge contacts are of uniform force and are not altered in significant amount by intentional or unintentional alteration of the throw by contact adjustment or wear. In sharp contrast is a former driving mechanism utilizing a relay movement, or any equivalent which requires auxiliary contacts to close, or amplitude of motion to be set, by an external control.

Electrically, the separation of charge and discharge circuits isolates spurious interference associated with the charge circuit from affecting the discharge circuit and the radio frequency energy generated in the discharge circuit from back-acting on other apparatus through the charge circuit.

In these ways I accomplish numerous objects of my invention.

Fig. 4 shows a simplified alternate arrangement of my pulse oscillator. The internal structure surrounding plunger 12 is the same as shownin Fig. 1 except for the magnetic circuit. In this alternate a ring-like permanent magnet 60 takes the place of coil 13. Magnetized with a N- (north) pole on the left face and a S (south) pole on the right and with plunger 12 constructed of hard steel and magnetized permanently N at left and S at right the plunger is normally held toward the magnet by magnetic attraction; consequently, against discharge contact 21. Coil14-is energized with alternating current, either from a multivibrator or similar means as shown in Fig. 3 or from a usual alternator 61 supplying essentially a sine wave as shown in Fig. 4. When the direction of current flow in the coil is such as to establish a strong N pole at the left of the coil and a corresponding S pole at the right, the attraction of the plunger to the permanent magnet will be overcome and the plunger will be attracted by the unlike pole relation to the electromagnet. This causes the discharge contact to be broken and contact to be made between the plunger and the charge contact 19. There will be one oscillation of the plunger for each full On coil. 14 is opposite to that shown dotted the field of the coil will aid in holding the plunger 12 against the discharge contact. It is desirable but not necessary that the magnitude of the alternating current in the coil be sufficiently large to overcome the attraction of the permanent magnet while the sine waveshape of current is still increasing at a rapid rate on the side of that waveshape rather than at or near the top thereof where the rate is slow. The desired condition causes the speed of transport to be high and also results in the dwell times at the charge and discharge contacts to be approximately equal. The latter factor is not of fundamental importance, how- .ever, since the period between discharges determines the repetition rate of the device as normally used. Also, the interval required for charging is usually very much shorter than the period of plunger motion, the latter being sixty cycles per second if alternator 61 represents the usual power circuit.

. The embodiment of Fig. 4 is also operative if the positions of the coil and permanent magnet are interchanged The plunger is constructed of hollow cylindrical shape with gas-tight end walls and of a light material such as aluminum so that a minimum pressure is required to translate it. Plunger has also been shown of smaller diameter and greater length than plunger 12 in Fig. 1 to illustrate the variation in shape previously mentioned. Platinum tip contacts, or contacts of an equivalent satisfactory material, are again used.

The space at each end of the plunger is gas-tight. Two passages, 66 and 67, lead from these spaces to opposite chambers of a pump body, constructed in two halves, 68 and 69. A diaphragm 70 separates the two gas-tight chambers. A follower 71 bears against one side of the diaphragm and a spring 72 against the other. Cam 73 is revolved by motor 74, which results in an alternating compression and rarefaction in the chambers of the pump, hence pneumatic energy to drive plunger 65 back and forth as it was before by magnetic means. It is to be noted that the pump does not have valves and that a pressure is not built up continuously in one direction as is the case with usual pumps.

The working fluid is dry air, dry nitrogen or other inert gases known for maintaining proper electrical con tact conditions. The system may be filled at more than atmospheric pressure to obtain known improvement in contact are performance.

The remainder of the charge and discharge circuits are the same as in previous embodiments. In both Figs. 4 and 5 the charging source shown connected to lead 26 in Fig. 3 is employed and the radio frequency output is taken from between inner coaxial conductor 5 and the surrounding outer conductor.

The pneumatic model of my pulse generator is seen to also possess the desirable self-adjustment of contact wear attribute previously referred to.

In Fig. 5 the disk resistor 28 of Figs. 1, 2 and 3 has been omitted When present, the load impedance is composed of the characteristic impedance of the coaxial line and the resistance of the disk, in parallel. When omitted, the surge impedance of the transmission line alone is utilized. Stated qualitatively in another way, the charge of the relatively small capacitance of the plunger flows into the relatively large capacitance of the line. The transmission line should be sufficiently long to contain several wavelengths corresponding to that of the pulse, of which the distance over plunger 65 corresponds to a quarter wavelength as described in discussing plunger 12. The calibrator line impedance, represented by the plunger as the inner conductor and line 1 as the outer conductor, is made smaller than the output transmission line impedance by the factor of 0.74 in order that the output per unit bandwidth shall be uniform to the highest practical radio frequency. Conversely, the calibrator line impedance can be made larger than the transmission line impedance by a factor of 1.35 to achieve the same result. Values other than these may be used, of course, should some other parameter than uniformity of response be of prime importance.

It will be understood that a sine wave electronic oscillator having any desirable operating frequency may be utilized in my invention instead of the multivibrator of Fig. 3 or the alternator of Fig. 4 for the electro-magnetically actuated embodiments. A relatively large amplitude of electrical energy therefrom is preferable, as mentioned in connection with the alternator operation.

Specific values have been given to certain independent variables in this specification in order to most fully teach how the invention may be embodied. Wide variation may be taken from such values and changes in the details of the electrical circuits and in the size, shape, proportions and arrangement of parts may be made without departing from the spirit of my invention.

Having thus fully described my invention and the man ner in which it is to be practiced, I claim:

1. An electrical pulse oscillator comprising a single movable plunger, a conductive sheath enclosing said plunger, said sheath electrically insulated from said plunger, means to electrically charge said plunger, other means to move said plunger to accept a charge from said means to charge, further means to discharge said plunger, means to move said plunger for the discharge thereof to said means to discharge, the energy of said discharge electrically exciting the recited structure of plunger and sheath at radio frequency by current flow over the outer surface of said plunger adjacent the inner surface of said sheath and still further means to move said plunger back to said charge means to again accept a charge.

2. An electrical pulse oscillator comprising a single movable element of fixed shape, a conductive tube surrounding said element, means to insulate said element from said tube, means to electrically charge said element located adjacent to said element, means to electrically discharge said element located adjacent thereto and opposite said means to charge with respect to said element, further means for causing said element to mechanically oscillate between said charge and said discharge means, at each discharge a radio frequency wave being generated by the electrical energy of said discharge flowing between said element and said conductive tube.

3. A pulse generator of radio frequency electrical energy comprising only one electrically chargeable mechanically movable element, an electrically chargeable member symmetrically surrounding said element and extending therebeyond, means to insulate said element from said member, means to charge said element located adjacent to said element, means to discharge said element adjacent to said element and opposite to said charge means, means to mechanically oscillate said element between said charge and said discharge means for the alternation of the state of charge thereof, each discharge of said element inaugurating an alternating electrical wave of radio frequency between said element and said member.

4. In an oscillator for producing damped wave-trains of electrical energy, a single movable conductive element, means to charge said element to an electrical potential, means to transport said element with said charge to a second position, means contacting said element at said second position to discharge the same, an annular conductive electric wave path adjacent said element at said discharge means and an outer'conductor coaxial with said element so constituted that an electric wave flows over the surface of said element from the location of the contact at said second position to the opposite sructural limit of said element and back to said location of said contact, and means to rectilinearly transport said element from said second position to the original position, one wave-train being produced upon said outer conductor for each said discharge of said element.

5. An oscillator for producing pulses of electrical energy of radio frequency comprising a hollow conductive tubular member, a single conductive cylindrical element coaxially disposed within said member, an insulator separating said element from said member, a first contact near said element, high impedance means for establishing an electrical potential upon said contact, a second contact near said element opposite said first contact, electrical impedance means related to said member connected to said second contact, means to oscillate said element between said first and said second contacts, each connection of said element with said first contact eifecting an electrical charge thereon, each connection of said element with said second contact eifect-ing electrical discharge of said element, said discharge in flowing between said element and said member being modified to oscillatory electrical energy of radio frequency.

6. An oscillator for producing damped radio frequency wave trains of electrical energy comprising a single movable cylindrical metallic element of fixed length, a hollow cylindrical metallic tube surrounding said element and extending therebeyond, a tubular insulator between said element and said tube, a first contact adjacent said movable element, a resistor connected to said contact, a source of voltage connected to said resistor, a second contact oppositely adjacent said movable element, said contacts spaced a distance greater than the fixed dimension of said movable element therebetween, said second contact connected to a cylindrical metallic conductor positioned within said extended tube, said conductor having a smaller diameter than the diameter of said element, energy means for oscillating said element from said first to said second contact and from said second to said first contact, the configuration of said element, of said surrounding metallic tube and of said metallic conductor being such as to cause the electrical energy of each discharge of said movable element at said second contact to be converted to oscillatory wave energy by flowing over said element and thence flowing along said metallic conductor.

7. A pulse generator for producing recurrent damped wave trains of radio frequency electrical energy comprising a single movable cylindrical metallic element, contacts coaxially positioned upon opposite faces of said element, a hollow cylindrical metallic tube surrounding said element and extending beyond both extremities thereof, a tubular insulator between said element and said tube stationary with respect to said tube, a charge contact closely adjacent said movable element and coaxially related to said contacts thereon, a resistor connected to said charge contact, a capacitor connected to said resistor opposite said connection to said charge contact, a source of voltage of reversible polarity connected to said resistor and said capacitor at the junction thereof, a discharge contact closely adjacent said movable element on the face opposite said charge contact, said charge and discharge contacts spaced further apart than the axial distance between said contacts positioned upon opposite faces of said element, said discharge contact connected to a cylindrical metallic conductor coaxially positioned within said hollow tube extended, said conductor having a smaller diameter than the diameter of said element, alternating energy means for reversibly linearly moving said element between said charge and said discharge contacts, each connection of said element with said charge contact charging said element to approximately the potential of said source of voltage, each connection" of said element with said discharge contact discharging said element, said discharge flowing over said element as an electric wave of radio frequency and thence along the transmission line composed of said cylindrical conductor and said hollow tube extended.

8. A pulse oscillator for producing radio frequency energy comprising a single movable ferromagnetic plunger, means to charge said plunger adjacent thereto, means to discharge said plunger oppositely adjacent thereto, means to magnetically oscillate said plunger between said charging and said discharging means, and an electric wave transmission line embodying said plunger for forming energy of radio frequency from the energy of each discharge of said plunger.

9. In an electrical pulse oscillator for producing energy of radio frequency a rigidly constituted movable conductive plunger, an insulating tube surrounding said plunger, a conductive tube surrounding said insulating tube and extending coaxially beyond said plunger, means to give said plunger an oscillatory motion of translation within said tubes, other means to impart an electric charge to said plunger at one extreme of said motion, further means to discharge said plunger at the other extreme of said motion and means comprised of said plunger, an annular conductor in contact with said conductive tube and said conductive tube to convert the electrical energy of said discharge to oscillatory energy of radio frequency.

10. In an electrical pulse oscillator for generating radio frequency energy a single movable conductive cylindrical plunger, a conductive tube insulated from and coaxially surrounding-said plunger and extending therebeyond, cylindrical contacts coaxial with and of small diameter relativetothat of said plunger attached to opposite faces thereof, coacting flat disk contacts coaxially supported by but insulated from said tube adjacent each said cylindri'cal contact, the distance between said disk contacts being greater than the distance between the extremities of said cylindricalcontacts, one said disk contact connected to an electrical charging circuit, the other said disk contact connected to a disk-shaped resistor, said resistor'connecting in turn to said tube and to a conductor coaxially contained therein, means to mechanically oscillate said plunger between said disk contacts for the charge and discharge thereof, said discharge flowing through said disk resistor and along said plunger and tube adjacent thereto, said' flow resulting in energy of said discharge becoming energy of radio frequency.

11. In combination, in an electrical pulse oscillator for producing radio frequency energy, a single movable conductive ferromagnetic plunger, an enclosing conductive tube therearound, means to electrically insulate said plunger from said tube, and dual magnetic-field-producing elements surrounding said tube spaced on opposite sides of said plunger, alternating electrical energy means connected to at least one of said dual elements for alternating the direction of the magnetic field produced thereby, means to electrically charge and to discharge said plunger, said alternations of direction of said field efiFecting to and fro motion of said plunger for the alternate charge and discharge thereof, and means including said plunger and tube for converting the electrical energy of eachsaid discharge to oscillatory energy of radio frequency.

12. A generator of radio frequency pulse energy comprising only one movable magnetized plunger, a hollow cylinder containing said plunger, insulating means therebetween, means to electrically charge said plunger adjacent thereto, means to electrically discharge said plunger oppositely adjacent thereto, a permanent magnet adjacent said plunger, an electromagnet oppositely adjacent said plunger, means to intermittently excite said electromagnet to a magnetic intensity greater than that of said permanent magnet, said excitation causing said plunger to move between said charge and said discharge means for the charge and discharge thereof, each said discharge forming a pulse of radio frequency energy.

13. A pulse oscillator for producing radio frequency energy comprising a sole movable magnetized conductive plunger, a hollow conductive member containing said plunger, an insulator separating said plunger from said member, means to electrically charge said plunger adjacent thereto, means to electrically discharge said plunger to said member adjacent said plunger opposite said means to charge, the distance between said means to charge and said means to discharge being greater than the dimension of said plunger therebetween, a permanent magnet of magnetic polarity to attract said plunger adjacent said plunger, an electromagnet adjacent said plunger oppositely disposed from said permanent magnet, means to periodically electrically excite said electromagnet to create an attractive magnetic force upon said plunger greater than that exerted by said permanent magnet, said forces effecting oscillatory movement of said plunger between said means to charge and said means to discharge said plunger, each said discharge thereof forming a radio frequency wave between said plunger and said containing member.

14. A pulse generator for producing recurrent damped trains of radio frequency energy comprising a single permanently magnetized movable conductive cylindrical plunger, contacts coaxially located upon opposite faces of said plunger, an insulating sleeve surrounding said plunger, an outer hollow conductive cylinder surrounding said sleeve and extending coaxially beyond said plunger,

a discharge contact located adjacent one said plunger contact, said discharge contact also connected to another cylindrical conductor coaxially disposed within said outer cylinder as extended, the diameter of said other conductor being different than that of said plunger, a charge contact located adjacent the other said plunger contact and spaced therefrom such that not more than one of said charge and discharge contacts connect to said plunger contacts at any time, a source of voltage, a radio frequency filter connects ed to said source and to said charge contact establishing conductive connection between said source and saidcontact, an annular permanent magnet surrounding said conductive cylinder having poles on opposite faces, said magnet positioned adjacent one said contact, an electromagnet, said electromagnet positioned adjacent the other said contact, said magnetic structure holding said plunger against one said contact, a source of alternating current, said source connected to said electromagnet, the magnetic field of said electromagnet opposing and overcoming the field of said permanent magnet at the position of said plunger during one interval of each cycle of said alternating current, said plunger moving from said one contact to the other contact for the duration of said interval, each connection of said plunger with said charge contact effecting an electrical charge thereon, each connection of said plunger with said discharge contact effecting electrical discharge of said plunger, said discharge flowing over said plunger and thence along the transmission line composed of said other cylindrical conductor coaxially disposed within said outer cylinder as extended.

15. A pulse oscillator for producing electromagnetic wave energy comprising a single movable piston, means to electrically charge said piston, said means positioned adjacent one end thereof, means to electrically discharge said piston, said means positioned adjacent the other end thereof, a closed pneumatic circuit for increasing the differential pressure across said piston in one direction for moving said piston in contact with said charge means and for increasing said pressure in the opposite direction for moving said piston in contact with said discharge means, and a conductor surrounding said plunger and insulated therefrom for forming an electric wave from the electrical energy of each discharge.

16. A pulse generator for producing oscillatory electrical energy of radio frequency comprising a single movable electrically conductive piston, a hollow cylinder coaxially containing said piston and extending therebeyond, electrical insulating means between said cylinder and said piston, means to electrically charge said piston positioned adjacent one end thereof, means to electrically discharge said piston positioned adjacent the other end thereof, a gas-tight element adjacent each end of said piston, a pumplike chamber, a diaphragm dividing said chamber into approximately equal volumes, a passage from each said volume to one space formed between said gas-tight element and said piston, said structure constituting a closed pneumatic system, a gaseous working substance in said system, means for displacing said diaphragm in one direction, said displacement causing said piston to move into contact with said charge means, said means for displacing adapted to subsequently displace said diaphragm in the direction opposite to that previously recited, said opposite displacement causing said piston to move into contact with said discharge means, the electrical discharge of said piston thus occasioned initiating a wave of radio frequency energy flowing between said piston and said hollow cylinder.

17. The pulse generator of claim 16 wherein said means for displacing said diaphragm comprises a springopposed follower in mechanical contact with said diaphragm, a cam in contact with said follower, and a motor, said cam attached thereto for the rotation thereof.

18. A pulse generator for producing recurrent wave trains of electrical energy of radio frequency comprising a movable ferromagnetic plunger, only one hollow cylin- 1 1 (let containing said plunger, electrical insulating means therebetween, means to electrically charge said plunger positioned adjacent thereto in the movable direction thereof, means to electrically discharge said plunger positioned oppositely adjacent thereto, two coils of wire surrounding said hollow cylinder on opposite sides of said plunger, a ferromagnetic structure enclosing said coils save adjacent said plunger, a relaxation oscillator having a vacuum tube with two cathodes, one of each said coils connected in one of each said cathode circuits, said vacuum tube having a plurality of other electrodes coactive with each of said cathodes, circuits of substantially equal time constant connected to each said plurality for causing substantially a square wave of current to flow in each of said coils, said flow coacting with said plunger to produce rectilinearly oscillatory motion thereof between said means to charge and said means to discharge said plunger, each said discharge initiating a wave train of radio frequency energy flowing between said plunger and said hollow cylinder.

19. An electro-mechanical pulse oscillator for producing damped wave-trains of radio frequency energy comprising a single movable ferromagnetic metallic plunger of cylindrical shape, small contacts 'coaxially located upon opposite faces of said plunger, an insulating sleeve surrounding said plunger, the outer cylindrical tube of a coaxial radio frequency transmission line surrounding said insulating sleeve, a discharge contact larger than said plunger contacts and a disk-like resistor located coaxially with and near one said plunger contact, said discharge contact also connected to another cylindrical inner conductor of said coaxial line, said inner conductor having a diameter smaller than the diameter of said plunger, a larger charge contact located coaxially with and near the other said plunger contact, said charge contact spaced therefrom such that not more than one of said charge and discharge contacts are connected to said plunger contacts at any time, a resistor connected to said charge contact and to a source of voltage, a capacitor connected from the junction between said resistor and said source to said outer cylindrical tube, two multi-turn coils of wire surrounding said outer tube on opposite sides of said plunger, a ferromagnetic structure enclosing said coils save adjacent said plunger, a multivibrator having a vac, uum tube with two cathodes, one of each said coils connected in one of each said cathode circuits, current flowing through one said coil during one half of a cycle of alternating current of said multivibrator causing said plunger to be attracted to said charging contact as a consequence of said plunger moving to complete the ferromagnetic circuit associated with said coil, and current flowing through the other coil during the next half of the cycle of alternating current of said multivibrator causing said plunger to be attracted to said discharging contact as a consequence of moving to complete the ferromagnetic circuit associated with said other coil, a damped pulse Wave of radio frequency energy being produced in the radio frequency path surrounding said plunger and propagated along the coaxial transmission line including said inner conductor of smaller diameter and said outer cylindrical tube.

Hansell Apr. 27, 1937 Lindenblad Jan. 19, 1943 

